Users Guide

Fabric OS Administrator’s Guide 427
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Chapter
15
Bottleneck Detection
In this chapter
•Bottleneck detection overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427
•Supported configurations for bottleneck detection . . . . . . . . . . . . . . . . . . 429
•Enabling bottleneck detection on a switch . . . . . . . . . . . . . . . . . . . . . . . . . 431
•Displaying bottleneck detection configuration details . . . . . . . . . . . . . . . . 431
•Setting bottleneck detection alerts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433
•Changing bottleneck detection parameters . . . . . . . . . . . . . . . . . . . . . . . . 435
•Advanced bottleneck detection settings . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
•Excluding a port from bottleneck detection. . . . . . . . . . . . . . . . . . . . . . . . . 440
•Displaying bottleneck statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
•Disabling bottleneck detection on a switch. . . . . . . . . . . . . . . . . . . . . . . . . 442
Bottleneck detection overview
A bottleneck is a port in the fabric where frames cannot get through as fast as they should. In other
words, a bottleneck is a port where the offered load is greater than the achieved egress
throughput. Bottlenecks can cause undesirable degradation in throughput on various links. When a
bottleneck occurs at one place, other points in the fabric can experience bottlenecks as the traffic
backs up.
Bottleneck detection is configured on a per-switch basis, with optional per-port exclusions.
Bottleneck detection is disabled by default. The best practice is to enable bottleneck detection on
all switches in the fabric, and leave it on to continuously gather statistics. Bottleneck detection
does not require a license.
The bottleneck detection feature enables you to do the following:
• Prevent degradation of throughput in the fabric.
The bottleneck detection feature alerts you to the existence and locations of devices that are
causing latency. If you receive alerts for one or more F_Ports, use the CLI to check whether
these F_Ports have a history of bottlenecks.
• Reduce the time it takes to troubleshoot network problems.
If you notice one or more applications slowing down, you can determine whether any latency
devices are attached to the fabric and where. You can use the CLI to display a history of
bottleneck conditions on a port. If the CLI shows above-threshold bottleneck severity, you can
narrow the problem down to device latency rather than problems in the fabric.